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Miguel Ojeda351f683b2018-02-17 20:33:13 +01001// SPDX-License-Identifier: GPL-2.0+
Geert Uytterhoevend47d8832017-03-10 15:15:21 +01002/*
3 * HD44780 Character LCD driver for Linux
4 *
5 * Copyright (C) 2000-2008, Willy Tarreau <w@1wt.eu>
6 * Copyright (C) 2016-2017 Glider bvba
Geert Uytterhoevend47d8832017-03-10 15:15:21 +01007 */
8
9#include <linux/delay.h>
10#include <linux/gpio/consumer.h>
11#include <linux/module.h>
Randy Dunlapac316722018-06-19 22:47:28 -070012#include <linux/mod_devicetable.h>
Geert Uytterhoevend47d8832017-03-10 15:15:21 +010013#include <linux/platform_device.h>
14#include <linux/property.h>
15#include <linux/slab.h>
16
Masahiro Yamada75354282019-08-06 16:14:44 +090017#include "charlcd.h"
Lars Poeschel718e05e2020-11-03 10:58:05 +010018#include "hd44780_common.h"
Geert Uytterhoevend47d8832017-03-10 15:15:21 +010019
20enum hd44780_pin {
21 /* Order does matter due to writing to GPIO array subsets! */
22 PIN_DATA0, /* Optional */
23 PIN_DATA1, /* Optional */
24 PIN_DATA2, /* Optional */
25 PIN_DATA3, /* Optional */
26 PIN_DATA4,
27 PIN_DATA5,
28 PIN_DATA6,
29 PIN_DATA7,
30 PIN_CTRL_RS,
31 PIN_CTRL_RW, /* Optional */
32 PIN_CTRL_E,
33 PIN_CTRL_BL, /* Optional */
34 PIN_NUM
35};
36
37struct hd44780 {
38 struct gpio_desc *pins[PIN_NUM];
39};
40
Lars Poeschel66ce7d52020-11-03 10:58:04 +010041static void hd44780_backlight(struct charlcd *lcd, enum charlcd_onoff on)
Geert Uytterhoevend47d8832017-03-10 15:15:21 +010042{
Lars Poeschel2545c1c2020-11-03 10:58:06 +010043 struct hd44780_common *hdc = lcd->drvdata;
44 struct hd44780 *hd = hdc->hd44780;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +010045
46 if (hd->pins[PIN_CTRL_BL])
47 gpiod_set_value_cansleep(hd->pins[PIN_CTRL_BL], on);
48}
49
50static void hd44780_strobe_gpio(struct hd44780 *hd)
51{
52 /* Maintain the data during 20 us before the strobe */
53 udelay(20);
54
55 gpiod_set_value_cansleep(hd->pins[PIN_CTRL_E], 1);
56
57 /* Maintain the strobe during 40 us */
58 udelay(40);
59
60 gpiod_set_value_cansleep(hd->pins[PIN_CTRL_E], 0);
61}
62
63/* write to an LCD panel register in 8 bit GPIO mode */
64static void hd44780_write_gpio8(struct hd44780 *hd, u8 val, unsigned int rs)
65{
Janusz Krzysztofikb9762be2018-09-05 23:50:05 +020066 DECLARE_BITMAP(values, 10); /* for DATA[0-7], RS, RW */
67 unsigned int n;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +010068
Janusz Krzysztofikb9762be2018-09-05 23:50:05 +020069 values[0] = val;
70 __assign_bit(8, values, rs);
71 n = hd->pins[PIN_CTRL_RW] ? 10 : 9;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +010072
73 /* Present the data to the port */
Janusz Krzysztofik77588c12018-09-05 23:50:07 +020074 gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA0], NULL, values);
Geert Uytterhoevend47d8832017-03-10 15:15:21 +010075
76 hd44780_strobe_gpio(hd);
77}
78
79/* write to an LCD panel register in 4 bit GPIO mode */
80static void hd44780_write_gpio4(struct hd44780 *hd, u8 val, unsigned int rs)
81{
Janusz Krzysztofikb9762be2018-09-05 23:50:05 +020082 DECLARE_BITMAP(values, 6); /* for DATA[4-7], RS, RW */
83 unsigned int n;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +010084
85 /* High nibble + RS, RW */
Janusz Krzysztofikb9762be2018-09-05 23:50:05 +020086 values[0] = val >> 4;
87 __assign_bit(4, values, rs);
88 n = hd->pins[PIN_CTRL_RW] ? 6 : 5;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +010089
90 /* Present the data to the port */
Janusz Krzysztofik77588c12018-09-05 23:50:07 +020091 gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], NULL, values);
Geert Uytterhoevend47d8832017-03-10 15:15:21 +010092
93 hd44780_strobe_gpio(hd);
94
95 /* Low nibble */
Janusz Krzysztofikb9762be2018-09-05 23:50:05 +020096 values[0] &= ~0x0fUL;
97 values[0] |= val & 0x0f;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +010098
99 /* Present the data to the port */
Janusz Krzysztofik77588c12018-09-05 23:50:07 +0200100 gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], NULL, values);
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100101
102 hd44780_strobe_gpio(hd);
103}
104
105/* Send a command to the LCD panel in 8 bit GPIO mode */
Lars Poeschel2c6a82f2020-11-03 10:58:09 +0100106static void hd44780_write_cmd_gpio8(struct hd44780_common *hdc, int cmd)
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100107{
Lars Poeschel2545c1c2020-11-03 10:58:06 +0100108 struct hd44780 *hd = hdc->hd44780;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100109
110 hd44780_write_gpio8(hd, cmd, 0);
111
112 /* The shortest command takes at least 120 us */
113 udelay(120);
114}
115
116/* Send data to the LCD panel in 8 bit GPIO mode */
Lars Poeschel71ff7012020-11-03 10:58:08 +0100117static void hd44780_write_data_gpio8(struct hd44780_common *hdc, int data)
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100118{
Lars Poeschel2545c1c2020-11-03 10:58:06 +0100119 struct hd44780 *hd = hdc->hd44780;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100120
121 hd44780_write_gpio8(hd, data, 1);
122
123 /* The shortest data takes at least 45 us */
124 udelay(45);
125}
126
127static const struct charlcd_ops hd44780_ops_gpio8 = {
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100128 .backlight = hd44780_backlight,
Lars Poeschelb26deab2020-11-03 10:58:11 +0100129 .print = hd44780_common_print,
Lars Poescheld3a2fb82020-11-03 10:58:12 +0100130 .gotoxy = hd44780_common_gotoxy,
Lars Poeschel88645a82020-11-03 10:58:13 +0100131 .home = hd44780_common_home,
Lars Poeschel45421ff2020-11-03 10:58:14 +0100132 .clear_display = hd44780_common_clear_display,
Lars Poeschel01ec46d2020-11-03 10:58:17 +0100133 .init_display = hd44780_common_init_display,
Lars Poescheld2f21872020-11-03 10:58:18 +0100134 .shift_cursor = hd44780_common_shift_cursor,
135 .shift_display = hd44780_common_shift_display,
136 .display = hd44780_common_display,
137 .cursor = hd44780_common_cursor,
138 .blink = hd44780_common_blink,
139 .fontsize = hd44780_common_fontsize,
140 .lines = hd44780_common_lines,
Lars Poeschel339acb02020-11-03 10:58:20 +0100141 .redefine_char = hd44780_common_redefine_char,
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100142};
143
144/* Send a command to the LCD panel in 4 bit GPIO mode */
Lars Poeschel2c6a82f2020-11-03 10:58:09 +0100145static void hd44780_write_cmd_gpio4(struct hd44780_common *hdc, int cmd)
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100146{
Lars Poeschel2545c1c2020-11-03 10:58:06 +0100147 struct hd44780 *hd = hdc->hd44780;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100148
149 hd44780_write_gpio4(hd, cmd, 0);
150
151 /* The shortest command takes at least 120 us */
152 udelay(120);
153}
154
155/* Send 4-bits of a command to the LCD panel in raw 4 bit GPIO mode */
Lars Poeschel2c6a82f2020-11-03 10:58:09 +0100156static void hd44780_write_cmd_raw_gpio4(struct hd44780_common *hdc, int cmd)
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100157{
Janusz Krzysztofikb9762be2018-09-05 23:50:05 +0200158 DECLARE_BITMAP(values, 6); /* for DATA[4-7], RS, RW */
Lars Poeschel2545c1c2020-11-03 10:58:06 +0100159 struct hd44780 *hd = hdc->hd44780;
Janusz Krzysztofikb9762be2018-09-05 23:50:05 +0200160 unsigned int n;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100161
162 /* Command nibble + RS, RW */
Janusz Krzysztofikb9762be2018-09-05 23:50:05 +0200163 values[0] = cmd & 0x0f;
164 n = hd->pins[PIN_CTRL_RW] ? 6 : 5;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100165
166 /* Present the data to the port */
Janusz Krzysztofik77588c12018-09-05 23:50:07 +0200167 gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], NULL, values);
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100168
169 hd44780_strobe_gpio(hd);
170}
171
172/* Send data to the LCD panel in 4 bit GPIO mode */
Lars Poeschel71ff7012020-11-03 10:58:08 +0100173static void hd44780_write_data_gpio4(struct hd44780_common *hdc, int data)
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100174{
Lars Poeschel2545c1c2020-11-03 10:58:06 +0100175 struct hd44780 *hd = hdc->hd44780;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100176
177 hd44780_write_gpio4(hd, data, 1);
178
179 /* The shortest data takes at least 45 us */
180 udelay(45);
181}
182
183static const struct charlcd_ops hd44780_ops_gpio4 = {
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100184 .backlight = hd44780_backlight,
Lars Poeschelb26deab2020-11-03 10:58:11 +0100185 .print = hd44780_common_print,
Lars Poescheld3a2fb82020-11-03 10:58:12 +0100186 .gotoxy = hd44780_common_gotoxy,
Lars Poeschel88645a82020-11-03 10:58:13 +0100187 .home = hd44780_common_home,
Lars Poeschel45421ff2020-11-03 10:58:14 +0100188 .clear_display = hd44780_common_clear_display,
Lars Poeschel01ec46d2020-11-03 10:58:17 +0100189 .init_display = hd44780_common_init_display,
Lars Poescheld2f21872020-11-03 10:58:18 +0100190 .shift_cursor = hd44780_common_shift_cursor,
191 .shift_display = hd44780_common_shift_display,
192 .display = hd44780_common_display,
193 .cursor = hd44780_common_cursor,
194 .blink = hd44780_common_blink,
195 .fontsize = hd44780_common_fontsize,
196 .lines = hd44780_common_lines,
Lars Poeschel339acb02020-11-03 10:58:20 +0100197 .redefine_char = hd44780_common_redefine_char,
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100198};
199
200static int hd44780_probe(struct platform_device *pdev)
201{
202 struct device *dev = &pdev->dev;
203 unsigned int i, base;
204 struct charlcd *lcd;
Lars Poeschel718e05e2020-11-03 10:58:05 +0100205 struct hd44780_common *hdc;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100206 struct hd44780 *hd;
Lars Poeschel718e05e2020-11-03 10:58:05 +0100207 int ifwidth, ret = -ENOMEM;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100208
209 /* Required pins */
210 ifwidth = gpiod_count(dev, "data");
211 if (ifwidth < 0)
212 return ifwidth;
213
214 switch (ifwidth) {
215 case 4:
216 base = PIN_DATA4;
217 break;
218 case 8:
219 base = PIN_DATA0;
220 break;
221 default:
222 return -EINVAL;
223 }
224
Lars Poeschel718e05e2020-11-03 10:58:05 +0100225 hdc = hd44780_common_alloc();
226 if (!hdc)
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100227 return -ENOMEM;
228
Lars Poeschel2545c1c2020-11-03 10:58:06 +0100229 lcd = charlcd_alloc();
Lars Poeschel718e05e2020-11-03 10:58:05 +0100230 if (!lcd)
231 goto fail1;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100232
Lars Poeschel718e05e2020-11-03 10:58:05 +0100233 hd = kzalloc(sizeof(struct hd44780), GFP_KERNEL);
234 if (!hd)
235 goto fail2;
236
237 hdc->hd44780 = hd;
238 lcd->drvdata = hdc;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100239 for (i = 0; i < ifwidth; i++) {
240 hd->pins[base + i] = devm_gpiod_get_index(dev, "data", i,
241 GPIOD_OUT_LOW);
242 if (IS_ERR(hd->pins[base + i])) {
243 ret = PTR_ERR(hd->pins[base + i]);
Lars Poeschel718e05e2020-11-03 10:58:05 +0100244 goto fail3;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100245 }
246 }
247
248 hd->pins[PIN_CTRL_E] = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
249 if (IS_ERR(hd->pins[PIN_CTRL_E])) {
250 ret = PTR_ERR(hd->pins[PIN_CTRL_E]);
Lars Poeschel718e05e2020-11-03 10:58:05 +0100251 goto fail3;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100252 }
253
254 hd->pins[PIN_CTRL_RS] = devm_gpiod_get(dev, "rs", GPIOD_OUT_HIGH);
255 if (IS_ERR(hd->pins[PIN_CTRL_RS])) {
256 ret = PTR_ERR(hd->pins[PIN_CTRL_RS]);
Lars Poeschel718e05e2020-11-03 10:58:05 +0100257 goto fail3;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100258 }
259
260 /* Optional pins */
261 hd->pins[PIN_CTRL_RW] = devm_gpiod_get_optional(dev, "rw",
262 GPIOD_OUT_LOW);
263 if (IS_ERR(hd->pins[PIN_CTRL_RW])) {
264 ret = PTR_ERR(hd->pins[PIN_CTRL_RW]);
Lars Poeschel718e05e2020-11-03 10:58:05 +0100265 goto fail3;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100266 }
267
268 hd->pins[PIN_CTRL_BL] = devm_gpiod_get_optional(dev, "backlight",
269 GPIOD_OUT_LOW);
270 if (IS_ERR(hd->pins[PIN_CTRL_BL])) {
271 ret = PTR_ERR(hd->pins[PIN_CTRL_BL]);
Lars Poeschel718e05e2020-11-03 10:58:05 +0100272 goto fail3;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100273 }
274
275 /* Required properties */
Geert Uytterhoevenc7c3f092017-03-23 14:25:37 +0100276 ret = device_property_read_u32(dev, "display-height-chars",
277 &lcd->height);
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100278 if (ret)
Lars Poeschel718e05e2020-11-03 10:58:05 +0100279 goto fail3;
Geert Uytterhoevenc7c3f092017-03-23 14:25:37 +0100280 ret = device_property_read_u32(dev, "display-width-chars", &lcd->width);
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100281 if (ret)
Lars Poeschel718e05e2020-11-03 10:58:05 +0100282 goto fail3;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100283
284 /*
285 * On displays with more than two rows, the internal buffer width is
286 * usually equal to the display width
287 */
288 if (lcd->height > 2)
Lars Poeschel2545c1c2020-11-03 10:58:06 +0100289 hdc->bwidth = lcd->width;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100290
291 /* Optional properties */
Lars Poeschel2545c1c2020-11-03 10:58:06 +0100292 device_property_read_u32(dev, "internal-buffer-width", &hdc->bwidth);
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100293
Lars Poeschel3fc04dd2020-11-03 10:58:07 +0100294 hdc->ifwidth = ifwidth;
Lars Poeschel71ff7012020-11-03 10:58:08 +0100295 if (ifwidth == 8) {
296 lcd->ops = &hd44780_ops_gpio8;
297 hdc->write_data = hd44780_write_data_gpio8;
Lars Poeschel2c6a82f2020-11-03 10:58:09 +0100298 hdc->write_cmd = hd44780_write_cmd_gpio8;
Lars Poeschel71ff7012020-11-03 10:58:08 +0100299 } else {
300 lcd->ops = &hd44780_ops_gpio4;
301 hdc->write_data = hd44780_write_data_gpio4;
Lars Poeschel2c6a82f2020-11-03 10:58:09 +0100302 hdc->write_cmd = hd44780_write_cmd_gpio4;
303 hdc->write_cmd_raw4 = hd44780_write_cmd_raw_gpio4;
Lars Poeschel71ff7012020-11-03 10:58:08 +0100304 }
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100305
306 ret = charlcd_register(lcd);
307 if (ret)
Lars Poeschel718e05e2020-11-03 10:58:05 +0100308 goto fail3;
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100309
310 platform_set_drvdata(pdev, lcd);
311 return 0;
312
Lars Poeschel718e05e2020-11-03 10:58:05 +0100313fail3:
314 kfree(hd);
315fail2:
316 kfree(lcd);
317fail1:
318 kfree(hdc);
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100319 return ret;
320}
321
322static int hd44780_remove(struct platform_device *pdev)
323{
324 struct charlcd *lcd = platform_get_drvdata(pdev);
325
326 charlcd_unregister(lcd);
Lars Poeschel333ff322021-07-14 13:02:28 +0200327 kfree(lcd->drvdata);
Andy Shevchenko41c8d0a2019-03-12 16:44:28 +0200328
Lars Poeschel718e05e2020-11-03 10:58:05 +0100329 kfree(lcd);
Geert Uytterhoevend47d8832017-03-10 15:15:21 +0100330 return 0;
331}
332
333static const struct of_device_id hd44780_of_match[] = {
334 { .compatible = "hit,hd44780" },
335 { /* sentinel */ }
336};
337MODULE_DEVICE_TABLE(of, hd44780_of_match);
338
339static struct platform_driver hd44780_driver = {
340 .probe = hd44780_probe,
341 .remove = hd44780_remove,
342 .driver = {
343 .name = "hd44780",
344 .of_match_table = hd44780_of_match,
345 },
346};
347
348module_platform_driver(hd44780_driver);
349MODULE_DESCRIPTION("HD44780 Character LCD driver");
350MODULE_AUTHOR("Geert Uytterhoeven <geert@linux-m68k.org>");
351MODULE_LICENSE("GPL");